=head1 NAME
perl - The Perl 5 language interpreter
=head1 SYNOPSIS
B<perl> S<[ B<-sTtuUWX> ]>
S<[ B<-hv> ] [ B<-V>[:I<configvar>] ]>
S<[ B<-cw> ] [ B<-d>[B<t>][:I<debugger>] ] [ B<-D>[I<number/list>] ]>
S<[ B<-pna> ] [ B<-F>I<pattern> ] [ B<-l>[I<octal>] ] [ B<-0>[I<octal/hexadecimal>] ]>
S<[ B<-I>I<dir> ] [ B<-m>[B<->]I<module> ] [ B<-M>[B<->]I<
'module...'
> ] [ B<-f> ]>
S<[ B<-C [I<number/list>] >]>
S<[ B<-S> ]>
S<[ B<-x>[I<dir>] ]>
S<[ B<-i>[I<extension>] ]>
S<[ [B<-e>|B<-E>] I<
'command'
> ] [ B<--> ] [ I<programfile> ] [ I<argument> ]...>
For more information on these options, you can run C<perldoc perlrun>.
=head1 GETTING HELP
The F<perldoc> program gives you access to all the documentation that comes
with
Perl. You can get more documentation, tutorials and community support
If you're new to Perl, you should start by running C<perldoc perlintro>,
which is a general intro
for
beginners and provides some background to help
you navigate the rest of Perl's extensive documentation. Run C<perldoc
perldoc> to learn more things you can
do
with
F<perldoc>.
For ease of access, the Perl manual
has
been
split
up into several sections.
=begin buildtoc
flag =g perluniprops perlmodlib perlapi perlintern
flag =go perltoc
flag =ro perlcn perljp perlko perltw
flag = perlvms
path perlfaq.* cpan/perlfaq/lib/
path perlglossary cpan/perlfaq/lib/
path perlxs(?:tut|typemap)? dist/ExtUtils-ParseXS/lib/
path perldoc cpan/Pod-Perldoc/lib/
aux a2p c2ph h2ph h2xs perlbug pl2pm pod2html pod2man s2p splain xsubpp
=end buildtoc
=head2 Overview
perl Perl overview (this section)
perlintro Perl introduction
for
beginners
perlrun Perl execution and options
perltoc Perl documentation table of contents
=head2 Tutorials
perlreftut Perl references short introduction
perldsc Perl data structures intro
perllol Perl data structures: arrays of arrays
perlrequick Perl regular expressions quick start
perlretut Perl regular expressions tutorial
perlootut Perl OO tutorial
for
beginners
perlperf Perl Performance and Optimization Techniques
perlstyle Perl style guide
perlcheat Perl cheat sheet
perltrap Perl traps
for
the unwary
perldebtut Perl debugging tutorial
perlfaq Perl frequently asked questions
perlfaq1 General Questions About Perl
perlfaq2 Obtaining and Learning about Perl
perlfaq3 Programming Tools
perlfaq4 Data Manipulation
perlfaq5 Files and Formats
perlfaq6 Regexes
perlfaq7 Perl Language Issues
perlfaq8 System Interaction
perlfaq9 Networking
=head2 Reference Manual
perlsyn Perl syntax
perldata Perl data structures
perlop Perl operators and precedence
perlsub Perl subroutines
perlfunc Perl built-in functions
perlopentut Perl
open
() tutorial
perlpacktut Perl
pack
() and
unpack
() tutorial
perlpod Perl plain old documentation
perlpodspec Perl plain old documentation
format
specification
perlpodstyle Perl POD style guide
perldiag Perl diagnostic messages
perllexwarn Perl warnings and their control
perldebug Perl debugging
perlvar Perl predefined variables
perlre Perl regular expressions, the rest of the story
perlrebackslash Perl regular expression backslash sequences
perlrecharclass Perl regular expression character classes
perlreref Perl regular expressions quick reference
perlref Perl references, the rest of the story
perlform Perl formats
perlobj Perl objects
perltie Perl objects hidden behind simple variables
perldbmfilter Perl DBM filters
perlipc Perl interprocess communication
perlfork Perl
fork
() information
perlnumber Perl number semantics
perlthrtut Perl threads tutorial
perlport Perl portability guide
perllocale Perl locale support
perluniintro Perl Unicode introduction
perlunicode Perl Unicode support
perlunifaq Perl Unicode FAQ
perluniprops Index of Unicode properties in Perl
perlunitut Perl Unicode tutorial
perlebcdic Considerations
for
running Perl on EBCDIC platforms
perlsec Perl security
perlmod Perl modules: how they work
perlmodlib Perl modules: how to
write
and
use
perlmodstyle Perl modules: how to
write
modules
with
style
perlmodinstall Perl modules: how to install from CPAN
perlnewmod Perl modules: preparing a new module
for
distribution
perlpragma Perl modules: writing a user pragma
perlutil utilities packaged
with
the Perl distribution
perlfilter Perl source filters
perldtrace Perl's support
for
DTrace
perlglossary Perl Glossary
=head2 Internals and C Language Interface
perlembed Perl ways to embed perl in your C or C++ application
perldebguts Perl debugging guts and tips
perlxstut Perl XS tutorial
perlxs Perl XS application programming interface
perlxstypemap Perl XS C/Perl type conversion tools
perlclib Internal replacements
for
standard C library functions
perlguts Perl internal functions
for
those doing extensions
perlcall Perl calling conventions from C
perlmroapi Perl method resolution plugin interface
perlreapi Perl regular expression plugin interface
perlreguts Perl regular expression engine internals
perlapi Perl API listing (autogenerated)
perlintern Perl internal functions (autogenerated)
perliol C API
for
Perl's implementation of IO in Layers
perlapio Perl internal IO abstraction interface
perlhack Perl hackers guide
perlsource Guide to the Perl source tree
perlinterp Overview of the Perl interpreter source and how it works
perlhacktut Walk through the creation of a simple C code patch
perlhacktips Tips
for
Perl core C code hacking
perlpolicy Perl development policies
perlgit Using git
with
the Perl repository
=head2 Miscellaneous
perlbook Perl book information
perlcommunity Perl community information
perldoc Look up Perl documentation in Pod
format
perlhist Perl history records
perldelta Perl changes since previous version
perl5175delta Perl changes in version 5.17.5
perl5174delta Perl changes in version 5.17.4
perl5173delta Perl changes in version 5.17.3
perl5172delta Perl changes in version 5.17.2
perl5171delta Perl changes in version 5.17.1
perl5170delta Perl changes in version 5.17.0
perl5161delta Perl changes in version 5.16.1
perl5162delta Perl changes in version 5.16.2
perl5160delta Perl changes in version 5.16.0
perl5143delta Perl changes in version 5.14.3
perl5142delta Perl changes in version 5.14.2
perl5141delta Perl changes in version 5.14.1
perl5140delta Perl changes in version 5.14.0
perl5125delta Perl changes in version 5.12.5
perl5124delta Perl changes in version 5.12.4
perl5123delta Perl changes in version 5.12.3
perl5122delta Perl changes in version 5.12.2
perl5121delta Perl changes in version 5.12.1
perl5120delta Perl changes in version 5.12.0
perl5101delta Perl changes in version 5.10.1
perl5100delta Perl changes in version 5.10.0
perl589delta Perl changes in version 5.8.9
perl588delta Perl changes in version 5.8.8
perl587delta Perl changes in version 5.8.7
perl586delta Perl changes in version 5.8.6
perl585delta Perl changes in version 5.8.5
perl584delta Perl changes in version 5.8.4
perl583delta Perl changes in version 5.8.3
perl582delta Perl changes in version 5.8.2
perl581delta Perl changes in version 5.8.1
perl58delta Perl changes in version 5.8.0
perl561delta Perl changes in version 5.6.1
perl56delta Perl changes in version 5.6
perl5005delta Perl changes in version 5.005
perl5004delta Perl changes in version 5.004
perlexperiment A listing of experimental features in Perl
perlartistic Perl Artistic License
perlgpl GNU General Public License
=head2 Language-Specific
=
for
buildtoc flag +r
perlcn Perl
for
Simplified Chinese (in EUC-CN)
perljp Perl
for
Japanese (in EUC-JP)
perlko Perl
for
Korean (in EUC-KR)
perltw Perl
for
Traditional Chinese (in Big5)
=head2 Platform-Specific
perlaix Perl notes
for
AIX
perlamiga Perl notes
for
AmigaOS
perlbeos Perl notes
for
BeOS
perlbs2000 Perl notes
for
POSIX-BC BS2000
perlce Perl notes
for
WinCE
perlcygwin Perl notes
for
Cygwin
perldgux Perl notes
for
DG/UX
perldos Perl notes
for
DOS
perlfreebsd Perl notes
for
FreeBSD
perlhaiku Perl notes
for
Haiku
perlhpux Perl notes
for
HP-UX
perlhurd Perl notes
for
Hurd
perlirix Perl notes
for
Irix
perllinux Perl notes
for
Linux
perlmacos Perl notes
for
Mac OS (Classic)
perlmacosx Perl notes
for
Mac OS X
perlnetware Perl notes
for
NetWare
perlopenbsd Perl notes
for
OpenBSD
perlos2 Perl notes
for
OS/2
perlos390 Perl notes
for
OS/390
perlos400 Perl notes
for
OS/400
perlplan9 Perl notes
for
Plan 9
perlqnx Perl notes
for
QNX
perlriscos Perl notes
for
RISC OS
perlsolaris Perl notes
for
Solaris
perlsymbian Perl notes
for
Symbian
perltru64 Perl notes
for
Tru64
perlvms Perl notes
for
VMS
perlvos Perl notes
for
Stratus VOS
perlwin32 Perl notes
for
Windows
=
for
buildtoc flag -r
=head2 Stubs
for
Deleted Documents
perlboot
perlbot
perltodo
perltooc
perltoot
=
for
buildtoc __END__
On a Unix-like
system
, these documentation files will usually also be
available as manpages
for
use
with
the F<man> program.
In general,
if
something strange
has
gone wrong
with
your program and you're
not sure where you should look
for
help,
try
making your code comply
with
where the trouble is.
=head1 DESCRIPTION
Perl officially stands
for
Practical Extraction and Report Language,
except
when
it doesn't.
Perl was originally a language optimized
for
scanning arbitrary
text files, extracting information from those text files, and printing
reports based on that information. It quickly became a good language
for
many
system
management tasks. Over the years, Perl
has
grown into
a general-purpose programming language. It's widely used
for
everything
from quick
"one-liners"
to full-scale application development.
The language is intended to be practical (easy to
use
, efficient,
complete) rather than beautiful (tiny, elegant, minimal).
Perl combines (in the author's opinion, anyway) some of the best
features of C, B<sed>, B<awk>, and B<sh>, so people familiar
with
those languages should have little difficulty
with
it. (Language
historians will also note some vestiges of B<csh>, Pascal, and even
BASIC-PLUS.) Expression syntax corresponds closely to C
expression syntax. Unlike most Unix utilities, Perl does not
arbitrarily limit the size of your data--
if
you've got the memory,
Perl can slurp in your whole file as a single string. Recursion is of
unlimited depth. And the tables used by hashes (sometimes called
"associative arrays"
) grow as necessary to prevent degraded
performance. Perl can
use
sophisticated pattern matching techniques to
scan large amounts of data quickly. Although optimized
for
scanning text, Perl also
has
many excellent tools
for
slicing
and dicing binary data.
But
wait
, there's more...
Begun in 1993 (see L<perlhist>), Perl version 5 is nearly a complete
rewrite that provides the following additional benefits:
=over 4
=item *
modularity and reusability using innumerable modules
Described in L<perlmod>, L<perlmodlib>, and L<perlmodinstall>.
=item *
embeddable and extensible
Described in L<perlembed>, L<perlxstut>, L<perlxs>, L<perlxstypemap>,
L<perlcall>, L<perlguts>, and L<xsubpp>.
=item *
roll-your-own magic variables (including multiple simultaneous DBM
implementations)
Described in L<perltie> and L<AnyDBM_File>.
=item *
subroutines can now be overridden, autoloaded, and prototyped
Described in L<perlsub>.
=item *
arbitrarily nested data structures and anonymous functions
Described in L<perlreftut>, L<perlref>, L<perldsc>, and L<perllol>.
=item *
object-oriented programming
Described in L<perlobj> and L<perlootut>.
=item *
support
for
light-weight processes (threads)
Described in L<perlthrtut> and L<threads>.
=item *
support
for
Unicode, internationalization, and localization
Described in L<perluniintro>, L<perllocale> and L<Locale::Maketext>.
=item *
lexical scoping
Described in L<perlsub>.
=item *
regular expression enhancements
Described in L<perlre>,
with
additional examples in L<perlop>.
=item *
enhanced debugger and interactive Perl environment,
with
integrated editor support
Described in L<perldebtut>, L<perldebug> and L<perldebguts>.
=item *
POSIX 1003.1 compliant library
Described in L<POSIX>.
=back
Okay, that's I<definitely> enough hype.
=head1 AVAILABILITY
Perl is available
for
most operating systems, including virtually
all Unix-like platforms. See L<perlport/
"Supported Platforms"
>
for
a listing.
=head1 ENVIRONMENT
See L<perlrun>.
=head1 AUTHOR
Larry Wall <larry
@wall
.org>,
with
the help of oodles of other folks.
If your Perl success stories and testimonials may be of help to others
who wish to advocate the
use
of Perl in their applications,
or
if
you wish to simply express your gratitude to Larry and the
Perl developers, please
write
to perl-thanks
@perl
.org .
=head1 FILES
"@INC"
locations of perl libraries
=head1 SEE ALSO
=head1 DIAGNOSTICS
Using the C<
use
strict> pragma ensures that all variables are properly
declared and prevents other misuses of legacy Perl features.
The C<
use
warnings> pragma produces some lovely diagnostics. One can
also
use
the B<-w> flag, but its
use
is normally discouraged, because
it gets applied to all executed Perl code, including that not under
your control.
See L<perldiag>
for
explanations of all Perl's diagnostics. The C<
use
diagnostics> pragma automatically turns Perl's normally terse warnings
and errors into these longer forms.
Compilation errors will
tell
you the line number of the error,
with
an
indication of the
next
token or token type that was to be examined.
(In a script passed to Perl via B<-e> switches,
each
B<-e> is counted as one line.)
Setuid scripts have additional constraints that can produce error
messages such as
"Insecure dependency"
. See L<perlsec>.
Did we mention that you should definitely consider using the B<
use
warnings>
pragma?
=head1 BUGS
The behavior implied by the B<
use
warnings> pragma is not mandatory.
Perl is at the mercy of your machine's definitions of various
operations such as type casting, atof(), and floating-point
output
with
sprintf
().
If your stdio requires a
seek
or
eof
between reads and writes on a
particular stream, so does Perl. (This doesn't apply to
sysread
()
and
syswrite
().)
While none of the built-in data types have any arbitrary size limits
(apart from memory size), there are still a few arbitrary limits: a
given
variable name may not be longer than 251 characters. Line numbers
displayed by diagnostics are internally stored as short integers,
so they are limited to a maximum of 65535 (higher numbers usually being
affected by wraparound).
You may mail your bug reports (be sure to include full configuration
information as output by the myconfig program in the perl source
tree, or by C<perl -V>) to perlbug
@perl
.org . If you've succeeded
in compiling perl, the L<perlbug> script in the F<utils/> subdirectory
can be used to help mail in a bug report.
Perl actually stands
for
Pathologically Eclectic Rubbish Lister, but
don't
tell
anyone I said that.
=head1 NOTES
The Perl motto is
"There's more than one way to do it."
Divining
how many more is left as an exercise to the reader.
The three principal virtues of a programmer are Laziness,
Impatience, and Hubris. See the Camel Book
for
why.